1. Field of the Invention
The present invention relates to a power charging device using multiple energy sources for supplying a predetermined amount of electrical power, wherein the multiple energy sources comprise a plurality of power sources, each having a different generating capacity and each output value thereof varying independently.
2. Description of the Related Art
Hitherto, various power sources, for example, dynamic energy, are used for power generation. For example, wind power generation is literally a power generation method using wind power and examples of windmills used for efficient generation include a propeller-type, a Darius-type, and a paddle-type. Also, thermal power generation and nuclear power generation have become the mainstreams of large-scale power generation. On the other hand, in a solar battery, light energy is directly converted into electrical energy for use. Although the utilization range of solar batteries is small, they are commonly used as power sources in electronic calculators and so forth.
In any case, a power source generating dynamic energy is required for performing charging. Generally, a single type of power source is used as the power source. That is, in wind power generation, a power source generated only by wind power is provided so as to obtain a large amount of power in a short period of time. This is the same for hydraulic power generation and thermal power generation. In this way, in a known charging system, charging is performed based on the power source from which uniform electrical power can be obtained, and thus a charging part needs to have only a charging function.
However, when different types (natures) of power sources are used, individual power sources often generate different amounts of electrical power. Therefore, the charging part needs to set a suitable output for each power source.
Further, since the plurality of power sources often vary without correlation, the charging system cannot perform efficient charging of a desired amount of electrical power. Accordingly, under the present circumstances, a separate charging function must be provided for each power source, thus causing complexity of device configuration and management, and a low utility value.
The present invention has been made in view of the above-described background, and it is an object of the present invention to provide a power charging device using multiple energy sources, in which a plurality of types of power source, each varying without correlation, are managed together so as to reduce complexity in charging system management, and in which efficient charging can be achieved using power output from the plurality of power sources with a single charging function, thereby simplifying the configuration of the device.
The present invention provides a power charging device using multiple energy sources for supplying a predetermined amount of electrical power, wherein the multiple energy sources comprise a plurality of power sources, each having a different generating capacity and each output value thereof varying independently. The device comprises output changing means which is provided for each of the power sources and which changes the variable output value to a desired output voltage value, and charging means which outputs the desired output voltage value to the output changing means and which supplies the power from the plurality of connected power sources.
According to the present invention, an input (voltage, for example) to the charging means can be made uniform by providing the output changing means, which changes the variable output value to the desired output value, for each of the power sources.
Further, in the present invention, the output changing means comprises a rectifier for rectifying an AC voltage of each of the power sources and an inverter which converts a DC voltage generated by rectification by the rectifier to frequency-adjustable AC and which converts the AC after the frequency adjustment to DC.
Most power sources generate AC. That is, the charging principle is basically the opposite to the principle of a motor which drives by changing polarities alternately, and thus the output voltage is AC. The AC is rectified by the rectifier so as to generate a DC voltage.
By converting the DC voltage to frequency-adjustable AC, the output voltage can be freely changed by frequency adjustment. By converting the adjusted AC to DC, the output voltage of each of the plurality of power sources, which have different output voltages, can be made uniform. The inverter functions to change DC to AC, and then to change AC to DC.
Also, in the present invention, the power charging device further comprises bias voltage supplying means for supplying a bias voltage to the inverter.
Since the inverter does not function when the input value is 0, a constant voltage must be supplied to the inverter even when the input from the power sources is 0. By supplying a predetermined voltage in advance from the bias voltage supplying means to the inverter, the inverter functions properly.
In the present invention, the inverter receives the desired output voltage value from the charging means and frequency adjustment is performed based on the desired output voltage value.
By the frequency adjustment in the inverter based on the desired output voltage value from the charging unit, the output voltage (effective value) of each of the plurality of power sources can be controlled so as to be uniform.
Further, in the present invention, the charging means comprises a maximum-current detector for detecting a maximum current value based on the electrical power supplied from the plurality of power sources, and a voltage feedback unit for converting the current value detected by the maximum-current detector to a voltage value and sending the voltage value to the inverter.
Each current value varies in accordance with the adjusted voltage by making the output voltage of each of the plurality of power sources uniform. Also, the time for a full charge cannot be estimated because the capacity of each power source varies. Accordingly, in a process where charging is gradually performed, the charging means adequately sets the output voltage of each power source based on the change in the charging voltage and the full-charge voltage.
Also, in the present invention, each of the maximum-current detector and the voltage feedback unit includes a phase-locked loop (PLL) circuit.
By using the PLL circuit, the difference between the charging voltage and the full-charge voltage which continuously changes can be recognized in real time, and the circuit configuration can be simplified.